:root{--brand:#76d9d1;--brand-hover:#5fcbc2;--ink:#162b2a;--muted:#596c69;--paper:#f5f7f4;--white:#fff;--line:#dbe6e3;--tint:#e7f7f3;--dark:#204e48;--radius:18px;--ease:cubic-bezier(.2,.7,.2,1);font-family:Arial,Helvetica,sans-serif;color:var(--ink);background:var(--paper);font-size:16px;font-synthesis:none}
/* Reserve the desktop scrollbar gutter when short and long tabs alternate. */
html{overflow-y:scroll;scrollbar-gutter:stable}
@supports(scrollbar-gutter:stable){html{overflow-y:auto}}
*{box-sizing:border-box}body{margin:0}a{color:inherit;text-decoration:none}button{font:inherit;cursor:pointer}a,button{touch-action:manipulation;transition:background .2s var(--ease),color .2s,border-color .2s,box-shadow .2s}a:focus-visible,button:focus-visible,summary:focus-visible,[role=tabpanel]:focus-visible{outline:3px solid #216c62;outline-offset:3px}h1,h2,h3,p{margin-top:0}h1,h2,h3{text-wrap:balance}p{line-height:1.7}svg{width:21px;height:21px;fill:none;stroke:currentColor;stroke-width:1.65;stroke-linecap:round;stroke-linejoin:round;vertical-align:middle;flex-shrink:0}img{max-width:100%;height:auto}[hidden]{display:none!important}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.skip-link{position:fixed;top:-80px;left:20px;z-index:100;background:var(--dark);color:white;padding:16px;border-radius:12px}.skip-link:focus{top:12px}main{max-width:1600px;margin:auto;padding:28px 36px 64px;outline:none}footer{display:flex;align-items:center;flex-wrap:wrap;justify-content:space-between;gap:16px;border-top:1px solid var(--line);padding:24px 36px;font-size:11px;color:var(--muted)}
.eyebrow{display:block;font-size:10px;line-height:1.5;font-weight:700;letter-spacing:1.5px;margin-bottom:16px;color:var(--muted)}.page-heading{margin:24px 0 32px;max-width:850px;animation:arrive .45s var(--ease) both}.page-heading h1{font-size:clamp(30px,3vw,46px);letter-spacing:-1.4px;line-height:1.12;margin-bottom:18px;overflow-wrap:anywhere}.page-heading p{color:var(--muted);font-size:16px}.back-link{display:inline-flex;gap:10px;align-items:center;font-size:13px;color:var(--muted);min-height:44px}.back-link:hover{color:var(--ink)}.primary,.secondary{display:inline-flex;align-items:center;justify-content:center;gap:12px;min-height:48px;padding:14px 20px;border:0;border-radius:12px;font-size:14px;font-weight:700;line-height:1.5;text-align:center}.primary{background:var(--brand);color:var(--ink)}.primary:hover{background:var(--brand-hover);box-shadow:0 4px 16px #204e4814}.secondary{background:var(--white);border:1px solid var(--line)}.secondary:hover{background:var(--tint)}.text-button{display:flex;align-items:center;gap:12px;min-height:48px;background:none;border:0;padding:12px 0;color:var(--dark);font-size:14px;font-weight:700}.text-button:hover{text-decoration:underline}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,290px),1fr));gap:24px;max-width:1040px}.lesson-card{max-width:520px;background:var(--white);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;animation:arrive .45s var(--ease) both}.card-cover{height:200px;background:linear-gradient(140deg,#fff,#e7f7f3);display:flex;align-items:center;justify-content:center;position:relative;overflow:hidden}.card-cover img{height:155px;width:auto}.cover-index{position:absolute;top:22px;left:24px;font-size:10px;font-weight:700;letter-spacing:1px}.play-round,.round-link{width:48px;height:48px;display:flex;align-items:center;justify-content:center;border-radius:50%;background:var(--white);flex-shrink:0}.play-round{position:absolute;right:24px;bottom:20px}.round-link{background:var(--tint)}.round-link:hover{background:var(--brand)}.card-body{padding:24px}.card-body h2{font-size:23px;line-height:1.3;letter-spacing:-.4px;margin-bottom:12px}.card-body a:hover{text-decoration:underline}.card-body p{font-size:15px;color:var(--muted)}.card-bottom{display:flex;align-items:center;justify-content:space-between;gap:16px;font-size:12px;margin-top:20px}
/* A single viewing workspace keeps the video and topic selection together. */
.lesson-header{margin:4px 0 20px;animation:arrive .4s var(--ease) both}.lesson-meta{display:flex;align-items:center;gap:10px;margin-bottom:8px;font-size:10px;letter-spacing:1px;font-weight:700;color:var(--muted)}.lesson-header h1{max-width:1050px;font-size:clamp(21px,1.8vw,28px);font-weight:700;letter-spacing:-.6px;line-height:1.25;margin:0}.duration-badge{display:inline-flex;gap:6px;align-items:center;font-size:11px;font-variant-numeric:tabular-nums;letter-spacing:0;font-weight:400}.duration-badge svg{width:14px;height:14px}.lesson-view main{padding-top:16px;padding-bottom:24px}.lesson-workspace{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(340px,1fr);gap:24px;align-items:start}.watch-column{min-width:0;position:sticky;top:24px;background:var(--white);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;box-shadow:0 8px 32px #204e4808}.video-wrap{aspect-ratio:16/9;background:#0e1918;overflow:hidden}.video-wrap video{width:100%;height:100%;display:block;object-fit:contain}.player-toolbar{display:flex;align-items:center;gap:16px;padding:14px 16px}.now-playing{display:flex;gap:12px;align-items:center;min-width:0;flex:1}.now-playing small{display:block;font-size:9px;font-weight:700;letter-spacing:1.2px;color:var(--muted);margin-bottom:7px}.now-playing strong{display:block;font-size:14px;line-height:1.5;text-wrap:balance}.fullscreen-button,.cinema-close{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:44px;padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:var(--white);color:var(--ink);font-size:12px;flex-shrink:0}.fullscreen-button:hover,.cinema-close:hover{background:var(--tint)}.fullscreen-button svg{width:18px;height:18px}.playback-note:empty{display:none}.playback-note{border-top:1px solid var(--line);padding:14px 20px;margin:0;font-size:12px;color:var(--muted);line-height:1.6;min-height:48px}
.lesson-details{align-self:start;min-width:0;border:1px solid var(--line);border-radius:var(--radius);background:var(--white);overflow:clip;box-shadow:0 8px 32px #204e4808}.content-tabs{display:flex;gap:4px;padding:8px;border-bottom:1px solid var(--line);background:#fbfdfc}.content-tabs button{flex:1;min-width:0;min-height:48px;padding:10px 8px;border:0;border-radius:12px;background:transparent;color:var(--muted);font-size:13px;font-weight:700;line-height:1.35}.content-tabs button:hover{background:var(--paper)}.content-tabs button[aria-selected=true]{background:var(--dark);color:white;box-shadow:0 3px 8px #204e4820}.content-tabs button:focus-visible{outline-offset:-3px}.detail-body{height:auto;overflow:visible}.detail-panel{position:relative;padding:24px;animation:panel-in .25s var(--ease) both;outline-offset:-4px!important}.detail-panel h2{font-size:23px;line-height:1.25;letter-spacing:-.6px;margin-bottom:12px}.detail-panel h2>span{font-size:12px;vertical-align:middle;display:inline-grid;place-items:center;min-width:26px;height:26px;background:var(--tint);color:var(--dark);border-radius:50%;letter-spacing:0;margin-left:4px}.detail-panel p{font-size:15px;line-height:1.75}.detail-panel>.eyebrow,.topics-intro .eyebrow{font-size:9px;letter-spacing:1.2px;margin-bottom:12px}.topics-help,.form-help,.assignment-empty p{color:var(--muted)}.detail-panel .topics-help{font-size:13px;margin-bottom:20px}.chapter-list{list-style:none;padding:0;margin:0;display:grid;gap:8px}.chapter-button{display:flex;align-items:flex-start;gap:12px;width:100%;min-height:48px;border:1px solid var(--line);border-radius:12px;background:var(--white);padding:12px;text-align:left;color:var(--ink)}.chapter-button:hover{background:#f5faf8;border-color:#8caaa3}.chapter-button[aria-current]{background:var(--tint);border-color:#438b86;box-shadow:inset 3px 0 0 var(--dark)}.chapter-button time{font-variant-numeric:tabular-nums;font-size:12px;font-weight:700;line-height:1.7;color:var(--dark);min-width:34px;padding-top:1px}.chapter-button>span{flex:1;min-width:0}.chapter-button strong{display:block;font-size:14px;line-height:1.5}.chapter-button small{display:block;font-size:12px;line-height:1.65;color:var(--muted);margin-top:6px}.chapter-button svg{width:16px;height:16px;margin-top:3px}.detail-panel .primary{width:100%;font-size:14px;margin-top:8px}.materials-section{border-top:1px solid var(--line);margin-top:28px;padding-top:24px}.materials-section h3{font-size:17px}.lesson-materials{list-style:none;padding:0;margin:0}.lesson-materials li+li{margin-top:12px}.lesson-materials a{justify-content:flex-start;overflow-wrap:anywhere;text-align:left;max-width:100%}.yandex-form{display:block;width:100%;height:850px;border:1px solid var(--line);border-radius:12px;margin-top:24px;background:white}
.chapter-insights{margin-top:20px;border-top:1px solid var(--line);padding-top:8px}.chapter-insights summary{min-height:48px;padding:14px 0;cursor:pointer;font-size:14px;line-height:1.5;font-weight:700;color:var(--dark)}.chapter-insights ol{padding-left:20px;margin:12px 0 0}.chapter-insights li{padding:12px 0}.chapter-insights h3{font-size:15px;line-height:1.5;margin-bottom:8px}.detail-panel .chapter-insights p{font-size:14px;line-height:1.7;margin:0;color:var(--muted)}
.panel{background:var(--white);border:1px solid var(--line);border-radius:var(--radius);padding:32px;margin-bottom:24px}.panel h2{font-size:24px;letter-spacing:-.5px;margin-bottom:16px}.panel p{font-size:15px;max-width:70ch}.panel .form-help{font-size:14px;margin-top:20px}.teacher-lessons{list-style:none;margin:0;padding:0}.teacher-lessons li{display:flex;align-items:center;justify-content:space-between;gap:24px;padding:20px 0;border-bottom:1px solid var(--line)}.teacher-lessons li:last-child{border:0}.teacher-lessons strong{line-height:1.5}.teacher-lessons li>div{min-width:0;overflow-wrap:anywhere}.teacher-lessons p{color:var(--muted);margin:8px 0 0}.teacher-lessons .secondary{flex-shrink:0}
@keyframes arrive{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}@keyframes panel-in{from{opacity:.2;transform:translateY(5px)}to{opacity:1;transform:translateY(0)}}@keyframes breathe{50%{box-shadow:0 0 0 7px var(--tint)}}
@media(max-width:1100px){main{padding:24px 28px 48px}.lesson-workspace{grid-template-columns:minmax(0,1.65fr) minmax(320px,1fr);gap:20px}.lesson-header h1{font-size:26px}}
@media(max-width:800px){main{padding:20px 24px 40px}.lesson-header{margin:2px 0 16px}.lesson-header h1{font-size:23px}.lesson-workspace{grid-template-columns:minmax(0,1fr);gap:16px}.watch-column{top:0;z-index:10;border-radius:16px}.video-wrap{max-height:40dvh}.player-toolbar{padding:12px 16px}.now-playing strong{font-size:13px}.now-playing small{font-size:8px;margin-bottom:4px}.playback-note{font-size:11px;padding:10px 16px;min-height:38px}.detail-panel{padding:24px}.content-tabs{padding:7px}.content-tabs button{font-size:14px}.chapter-button{padding:12px 16px;gap:16px}.chapter-button strong{font-size:15px}.chapter-button small{font-size:13px}.fullscreen-button{padding:10px}.fullscreen-button span{display:none}.teacher-lessons li{align-items:flex-start;flex-direction:column;gap:16px}.panel{padding:24px}footer{padding:24px}}
@media(max-width:520px){main{padding:16px 16px 40px}.page-heading{margin:16px 0 24px}.page-heading h1{font-size:32px;letter-spacing:-1px}.page-heading p{font-size:15px}.lesson-header h1{font-size:21px;letter-spacing:-.4px}.lesson-view main{padding-top:8px}.lesson-meta{margin-bottom:6px}.detail-panel{padding:20px 16px}.detail-panel p{font-size:16px}.chapter-button{gap:12px;padding:12px}.chapter-button svg{display:none}.chapter-button time{min-width:33px}.chapter-button strong{font-size:14px}.chapter-button small{font-size:13px}.detail-panel .topics-help{font-size:14px}.content-tabs button{font-size:12px}.now-playing strong{font-size:12px}.primary,.secondary{font-size:13px;padding:14px 16px}.teacher-lessons .secondary{width:100%}footer{padding:20px 16px;font-size:10px}}
/* Both the native API and rotation fallback use the same accessible controls. */
.cinema-open{overflow:hidden;scrollbar-gutter:auto}html:has(:fullscreen){overflow:hidden;scrollbar-gutter:auto}.watch-column.cinema-mode,.watch-column:fullscreen{position:fixed;inset:0;z-index:60;width:100%;height:100dvh;border:0;border-radius:0;background:#0e1918;display:flex;flex-direction:column;padding:env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left)}.cinema-mode .video-wrap,:fullscreen .video-wrap{flex:1;aspect-ratio:auto;max-height:none;min-height:0;width:100%}.cinema-mode .player-toolbar,:fullscreen .player-toolbar{flex-shrink:0;background:#0e1918;color:white;padding:8px 16px}.cinema-mode .now-playing small,:fullscreen .now-playing small{color:#b1c8c3}.cinema-mode .playback-note,:fullscreen .playback-note{display:none}.cinema-mode .fullscreen-button span,:fullscreen .fullscreen-button span{display:inline}.cinema-close{background:#204e48;color:white;border-color:#49746d}.cinema-close:hover{background:#2e625b}
@media(max-height:500px) and (orientation:landscape) and (pointer:coarse){.watch-column:not(.cinema-mode):not(:fullscreen) .video-wrap{max-height:65dvh}.watch-column:not(.cinema-mode):not(:fullscreen) .playback-note{display:none}.cinema-mode .now-playing,:fullscreen .now-playing{display:none}.cinema-mode .player-toolbar,:fullscreen .player-toolbar{justify-content:flex-end}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}

/* Transcript shares the page scroll and never moves focus to the video. */
.transcript-actions{display:flex;align-items:center;flex-wrap:wrap;gap:8px 16px;margin:16px 0}.transcript-actions .secondary{font-size:13px}.transcript-actions .text-button{font-size:13px}.detail-panel .transcript-help{font-size:14px;color:var(--muted)}.transcript-list{list-style:none;padding:0;margin:0}.transcript-list button{display:flex;align-items:flex-start;gap:14px;width:100%;min-height:48px;padding:14px 8px;border:0;border-bottom:1px solid var(--line);border-radius:8px;background:transparent;color:var(--ink);text-align:left;line-height:1.7;font-size:14px}.transcript-list time{min-width:36px;color:var(--dark);font-size:12px;font-variant-numeric:tabular-nums;padding-top:2px}.transcript-list span{min-width:0;overflow-wrap:anywhere}.transcript-list button:hover{background:var(--paper)}.transcript-list button[aria-current]{background:var(--tint);box-shadow:inset 3px 0 0 var(--dark)}
@media(max-width:520px){.content-tabs:has([aria-controls="transcript"]) button{font-size:11px;padding:8px 3px}.transcript-list button{font-size:15px;gap:10px}}

@media(max-width:800px){.transcript-list button,.chapter-button{scroll-margin-top:42dvh}}

/* Real lecture frames keep their full 16:9 composition; labels stay legible. */
.card-cover.has-cover{height:auto;aspect-ratio:16/9;background:#0e1918}.card-cover.has-cover img{display:block;width:100%;height:100%;object-fit:cover}.has-cover .cover-index{top:16px;left:16px;padding:7px 10px;border-radius:8px;background:#fff;color:var(--ink)}.has-cover .play-round{right:16px;bottom:16px;box-shadow:0 2px 12px #0002}

/* Keep the home footer at the viewport bottom, without stretching the lesson viewer. */
body{min-height:100dvh;display:flex;flex-direction:column}.main-shell{flex:1;display:flex;flex-direction:column;min-width:0}main{flex:1;width:100%}.lesson-view .main-shell{flex:none;display:block}.is-loading footer{visibility:hidden}

/* Preview playback is intentional, silent, and never replaces the lesson link. */
.cover-link{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;z-index:1}.card-preview{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;pointer-events:none}.is-previewing .cover-link>img{opacity:0}.preview-toggle{position:absolute;left:16px;bottom:16px;z-index:2;min-height:44px;padding:9px 14px;border:1px solid #fff;border-radius:10px;background:#fff;color:var(--ink);font-size:12px;font-weight:700;box-shadow:0 2px 12px #0002}.preview-toggle:hover{background:var(--tint)}.preview-toggle:disabled{font-size:10px;cursor:default}.chapter-button>.chapter-visual{position:relative;flex:none;width:80px;aspect-ratio:16/9;overflow:hidden;border-radius:7px;background:#0e1918}.chapter-visual img{display:block;width:100%;height:100%;object-fit:cover}.chapter-visual time{position:absolute;right:3px;bottom:3px;background:#10201ee6;color:#fff;font-size:10px;line-height:1.4;min-width:0;padding:1px 4px;border-radius:3px}.chapter-button:has(.chapter-visual){align-items:center}.chapter-button:has(.chapter-visual)>svg{display:none}@media(max-width:520px){.chapter-button>.chapter-visual{width:72px}}

.cover-link:focus-visible{outline-offset:-5px}

/* One shared header, a direct catalog, and a compact lecture workspace. */
.site-header{flex-shrink:0;border-bottom:1px solid var(--line);background:var(--white)}
.site-header-inner{max-width:1280px;margin:0 auto;padding:10px 32px;min-height:84px;display:flex;align-items:center;justify-content:space-between;gap:24px}
.site-brand{display:block;flex-shrink:0;border-radius:8px}.site-brand img{display:block;width:142px}
.header-actions{display:flex;align-items:center}.catalog-back{display:inline-flex;gap:9px;align-items:center;min-height:44px;padding:10px 14px;border:1px solid var(--line);border-radius:11px;background:var(--white);color:var(--dark);font-size:14px;font-weight:700}.catalog-back:hover{background:var(--tint);border-color:#9dbfb7}.catalog-back svg{width:18px;height:18px}
main{max-width:1280px;padding:32px 32px 56px}.lesson-view main{padding-top:24px;padding-bottom:24px}
footer{width:100%;max-width:1280px;margin:0 auto;padding:22px 32px;flex-shrink:0}
.cards{grid-template-columns:repeat(2,minmax(0,1fr));gap:28px;max-width:none}
.lesson-card{max-width:none;display:flex;flex-direction:column;box-shadow:0 6px 24px #183c3205;transition:border-color .2s,box-shadow .2s}
.lesson-card:hover{border-color:#b0c9c1;box-shadow:0 12px 32px #183c320b}
.card-cover{flex:none}.card-cover.has-cover{border-bottom:1px solid var(--line)}
.card-cover .cover-index{font-size:12px;letter-spacing:0;font-weight:700}.has-cover .cover-index{border-radius:8px;padding:6px 10px;box-shadow:0 2px 12px #0001}
.cover-link>img{transition:opacity .2s var(--ease),transform .4s var(--ease)}
.card-body{flex:1;display:flex;flex-direction:column;padding:24px}.card-body h2{font-size:24px;line-height:1.3;margin-bottom:12px;letter-spacing:-.55px}.card-body h2 a:hover{color:var(--dark);text-decoration:none}.card-body>p{font-size:15px;line-height:1.65;margin-bottom:22px}
.card-body>.resume-note{font-size:13px;color:var(--dark);margin:-8px 0 18px;display:flex;align-items:center;gap:8px}.resume-note:before{content:'';width:6px;height:6px;flex-shrink:0;border-radius:50%;background:#397f70}
.card-bottom{margin-top:auto;padding-top:20px;gap:16px;flex-wrap:wrap;border-top:1px solid var(--line)}
.card-meta{display:flex;align-items:center;gap:14px;color:var(--muted);font-size:13px;font-variant-numeric:tabular-nums}.card-meta>span{display:inline-flex;align-items:center;gap:6px}.card-meta>span+span{border-left:1px solid var(--line);padding-left:14px}.card-meta svg{width:15px;height:15px}
.lesson-action{display:inline-flex;align-items:center;justify-content:center;gap:9px;min-height:44px;padding:11px 15px;border-radius:11px;background:var(--dark);color:var(--white);font-size:14px;font-weight:700}.card-body .lesson-action:hover{background:#173f37;text-decoration:none}.lesson-action svg{width:18px;height:18px}
.preview-toggle{background:#102d28de;color:var(--white);border-color:#ffffff45;box-shadow:none;backdrop-filter:blur(8px)}.preview-toggle:hover{background:#153e35}.preview-toggle:focus-visible{outline-color:var(--white)}
.lesson-header{margin:0 0 22px;animation:arrive .3s var(--ease) both}.lesson-meta{font-size:12px;letter-spacing:0;font-weight:400;gap:10px;margin-bottom:8px}.lesson-header h1{font-size:clamp(21px,1.8vw,27px);max-width:none;line-height:1.3}.duration-badge{font-size:12px}
.lesson-workspace{grid-template-columns:minmax(0,1.65fr) minmax(360px,1fr);gap:28px}.watch-column{border-radius:18px;box-shadow:0 8px 28px #183c3208}.player-toolbar{padding:12px 16px;gap:12px}.now-playing{gap:0}.now-playing strong{font-size:14px;font-weight:400;line-height:1.5;text-wrap:pretty}.fullscreen-button{min-width:44px;min-height:44px;padding:9px 11px;font-size:12px}
.lesson-details{border:0;border-radius:0;background:transparent;box-shadow:none;overflow:visible}.content-tabs{padding:5px;gap:3px;border:1px solid var(--line);border-radius:14px;background:#eaf0ec;margin-bottom:12px}.content-tabs button{min-height:44px;border-radius:10px;font-size:13px;padding:9px 6px}.content-tabs button[aria-selected=true]{box-shadow:0 2px 6px #173f371a}.detail-panel{padding:20px;background:var(--white);border:1px solid var(--line);border-radius:16px}.detail-panel h2{font-size:21px;letter-spacing:-.4px}.detail-panel p{font-size:15px;line-height:1.7}
.chapter-list{gap:4px}.chapter-button{padding:10px 8px;border-color:transparent;border-radius:10px;min-height:64px}.chapter-button:hover{border-color:transparent;background:#f1f7f3}.chapter-button[aria-current]{border-color:transparent;background:var(--tint)}.chapter-button>.chapter-visual{width:76px}.chapter-button strong{font-size:14px;line-height:1.5}.chapter-visual time{font-size:11px}.chapter-insights{margin-top:14px}.chapter-insights summary{font-size:14px}
.transcript-actions{margin:16px 0 8px}.transcript-list button{font-size:14px;padding:12px 4px}.transcript-list time{font-size:12px}.detail-panel .transcript-help{font-size:13px;line-height:1.65}
@media(hover:hover) and (pointer:fine) and (prefers-reduced-motion:no-preference){.card-cover:hover .cover-link>img{transform:scale(1.015)}}
@media(max-width:1100px){.lesson-workspace{grid-template-columns:minmax(0,1.65fr) minmax(320px,1fr);gap:22px}}
@media(max-width:800px){.site-header-inner{padding:10px 24px;min-height:76px}.site-brand img{width:124px}main{padding:24px 24px 40px}.lesson-view main{padding-top:20px}.lesson-workspace{grid-template-columns:minmax(0,1fr);gap:18px}.watch-column{top:0;z-index:10}.lesson-header{margin-bottom:18px}.now-playing strong{font-size:13px}.detail-panel{padding:20px}.content-tabs button{font-size:13px}.cards{gap:20px}footer{padding:22px 24px}}
@media(max-width:680px){.cards{grid-template-columns:minmax(0,1fr)}.card-body h2{font-size:23px}}
@media(max-width:520px){.site-header-inner{padding:8px 16px;min-height:68px;gap:16px}.site-brand img{width:112px}.catalog-back{font-size:12px;padding:9px 11px;gap:7px}.catalog-back svg{width:16px;height:16px}main{padding:20px 16px 32px}.lesson-view main{padding-top:18px}.card-body{padding:20px}.card-body h2{font-size:22px}.card-body>p{font-size:15px;margin-bottom:20px}.card-bottom{gap:12px;padding-top:18px}.card-meta{font-size:12px;gap:10px}.card-meta>span+span{padding-left:10px}.lesson-action{font-size:13px;padding:10px 13px}.lesson-header h1{font-size:21px;line-height:1.3}.lesson-meta{font-size:11px}.duration-badge{font-size:11px}.detail-panel{padding:16px}.detail-panel p{font-size:15px}.content-tabs{padding:4px;gap:2px}.content-tabs:has([aria-controls=transcript]) button{font-size:12px;padding:8px 4px}.chapter-button{padding:10px 6px;gap:12px}.chapter-button>.chapter-visual{width:72px}.now-playing strong{font-size:12px}.player-toolbar{padding:11px 12px}.preview-toggle{left:12px;bottom:12px;font-size:12px;min-height:44px;padding:10px 12px}footer{padding:20px 16px}}
@media(prefers-reduced-motion:reduce){.cover-link>img{transition:none}.lesson-card,.lesson-header,.detail-panel{animation:none}}